Patent Literature 1 describes a method and device for measuring internal information of a scattering absorber. In the method and device described in this literature, light pulses of a plurality of wavelengths are incident on the scattering absorber, output light is detected by a photodetector, and the internal information of the scattering absorber is calculated on the basis of a detection result. When internal information is calculated, the internal information of the scattering absorber is calculated by calculating an absorption coefficient difference with a time-resolved integration measurement method (a TIS method) and a phase modulation measurement method (a PMS method) based on an MBL law according to a spectroscopic measurement method (an MVS method) using an optical path length average and variance or physical amounts corresponding thereto.
Non-Patent Literature 1 describes a method of measuring the concentrations of oxygenated hemoglobin and deoxygenated hemoglobin by using near infrared time-resolved spectroscopy. In the method described in this literature, a reduced scattering coefficient is set as a function of a wavelength by applying Mie scattering approximation and the concentration is calculated on the basis of each wavelength value.